To develop a system of voiding for patients with neurogenic bladders that will depend upon a prosthesis that will lie in the bladder neck and urethra containing either a mechanical or electronic valve that will allow for the internal storage of urine, periodic voiding, urinary continence and the maintenance of the integrity of the urinary tract by virtue of allowing voiding within normal physiologic and hydrodynamic pressure ranges. Although many of the new materials used in prosthetics are well tolerated by living tissues, none can survive indefinitely within the urinary tract and therefore the other key aspect of this proposal is that the prosthesis or that portion of the prosthesis which is exposed to the urine will be changeable without open surgical intervention. Experiments will include testing of reaction of animal tissue to proposed materials, development of the prosthesis, acute and chronic animal experiments in normal and paraplegic animals. Evaluation of the effect of the prosthesis on the urinary tract will be made by excretory urography, voiding cystourethrography, urine culture and autopsy. If satisfactory animal results can be obtained experiments in human subjects will be undertaken. Should a satisfactory prosthesis be developed it might well find application in the patient rendered incontinent of urine by accident or surgery.